Art of making electrotypes



Patented Apr. 14, 1925.

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enonenwnnnn MULLEN, or r nusnme, NEW YORK. ASSIGNOR TO JOHN 0. wranna ape, me, or new Yonmn. Y.. A conrona'rron or new roan.

in Drawing.

ART OF MAKING ELECTROTYPES.

Application filed May e, 1924. Serial No. 711,471.

To all whom it may concern: a

Be it known that I, GEORGE a' citizen of the United States, and resident of Flushing, borough and county of Queens, city and State of New York, have invented certain new and useful Improvements in the Art of Making Electrotypes', of which the following is a specification.

The invention relates to the manufacture of electrotypes and particularly to that phase which involves the backing up of the copper and/or nickel shell with type metal.

In the manufacture of electrotypcs which are extensively used in the graphic arts, an

' original printing surface, such as type mat- 'ter or an etched photo-engraving, is used as a dieor patrix .to form an impression by means of pressure, into a plastic substance such as wax or lead. When separated from the original. the medium which has received the impression is known as the matrix or mold and upon such matrices a thin shell oi copper and/or nickel is-deposited electrolytically by methods .Snch shells, usually about .010 to well known in the art.

.020 inch thick, are stripped from the mold and backed up with an alloy to form a printing foundatiomsuch alloy usually being of the composition: lead 94%, tin 3%, antimony In order to form a union of the backof the- 1 shell, it is customary to lay sheets of metal foil usually about .0015 inch thick, and

' composed'of to tin, balance lead,

covering the entire surface of the previously fluxed back of the shell, and the foil is melted; this operation 18 known as soldering;

or tinning.

It is the purpose 0 'f my present invention to render unnecessary this operation of soldering by use of foil.

using a soldering metal or a soldering operation I provide for a clearly defined layer between the copper and the type This layer of tin,

of pure tin metal. electrolytically shell, adheres with sufficient tenacity. to

serve-the purpose of producing commercial ele ctrotypes, although it requires far less consumption of tin than that which is used in the solder foil. My invention therefore, broadly stated, consists in applying a thin coating of electrol icallly the surface to be ack deposited tin on thereby effecting;

W. MnLLnN,

Instead of.

when appliedto the surface of the copper an economic gain by virtue of material and labor-saving and producin amore uni formly distributed solder union resulting in a more perfect printing material.

The usual procedure commonly employed in the manufacture of electrotypes' is .followed up to and including the electrolytic deposition of the metal shell, i. e. an impression is taken in a plastic medium, usually wax, which has been rendered electri cally'conductive. or lead. The edges and back of this mold are insulated and the mold, which is now referred to as a case isplaced in anelectrolytic bath for the deposition of a metallic shell thereon. The shell is usually of copper which'is deposited out oi a solution of a copper saltin the presence of acid serving as an electrolyte. although in many cases nickel is deposited out first in a separate bath by the passage of a suitable electric current through a soluas an electrolyte, metallic tin acting as anodes. whereas the case itsell'is the cathode and a suitable electric current passed until siillicicntthickness of tin has been deposited to form it firmly joined union oi shell and backing up metal. in the subsequent operation. When sullicient tin has been plated the case is removed l'rom the bath, the shell stripped from the matrix and the tinned back brushed with av lluxing solution of zinc chloride, or the like.

Since the nickeland copper baths'omploycd previously are acid in nature, I prefer-to. use an electrolyteconsisting of a solu' 'tion of tin sulphate in the p-resence'of a colloid anddree sulphuric acid; the use of an acid tin'bath allows of the placing of the case directly into the tin solution without any p e'paratory cleanimr or washing of the suriade\ to beplated. Without departing from thepurpose of my invention, an alkalinetin bath may be employed although uch procedure necessitates wishing to free the case of acid before placing-in the alkaline bath. a

I claim:

1. An electrotype comprising a printing surface constituted of a thin metal shell and a backing of type metal and, interposed between the shell and the backing, a thin layer of electrolytically deposited tin in' permanent adherence on one of its sides with the metal constituting the shell and on the'other side with the type metal backing.

2. That improvement in the art of making elcctrotypes which consists in forming avmetal shell, applying to the rear surface thereof in an electrolytic bath, a thin coating of tin and applying to the back of the said tin coating a backing of type metal.

3. That improvement in the art of making electrotypes which consists informing a metal shell in an electrolytic bath of acid character, removing the shell from the bath and placing it in a tin electrolyte, also of an acid character, and causing an electrolytic deposit of tin on the rear surface of the shell and thenbacking the tin coating with type metal.

4. That improvement in the art of making electrotypes which consists in forming a metal shell in an electrolytic bath of acid character, removing-the shell from the bath and placing it in a tin electrolyte consisting of a solution of tin sulphate in the presence of free sulphuric acid, causing an electro lytic deposit of tin on the rear surface of the shell and then backing the tin coating with type metal.

In testimony whereof I have hereunto set my hand.

GEORGE WILBUR MULLEN. 

